A New Approach to Solar Desalination Using a Humidification-Dehumidification Process for Remote Areas

Freshwater supply in remote areas has become a critical issue. This paper aims to introduce a new approach to a solar-powered humidification-dehumidification (HDH) desalination system. The design uses a solar collector, a thermal storage tank, and an HDH unit. The HDH works continuously by feeding water to absorb solar energy during the day and then relaying the desalination units with feed water at a top brine temperature (TBT) at night. The model predicts the amount of solar energy stored for the next day, and based on this, the amount of feed water that should be raised to the TBT is calculated. The system operation is carried out in two phases. During the day, the feed water absorbs the heat of solar energy, thereby increasing its temperature to TBT. This hot feed water is then kept in storage tanks. At night, the tank switches to discharging mode and starts feeding the HDH with the hot feed water. The system is designed so that the roles of the tank are rotated at sunset. To achieve the same TBT every day in response to changes in the available solar energy, the mass of the feed water is adjusted daily. The design is simulated using a dynamic model of the energy and mass balance resulting in an average daily production of 7.6 kg of fresh water per unit area of the solar collector. The daily average of the gain output and the recovery ratios are 0.3 and 0.09 respectively.

Automated summary

This study introduces a new solar-powered desalination system using a humidification-dehumidification (HDH) unit that operates continuously to absorb solar energy during the day and desalinate water at night. The system is designed to adjust the mass of feed water daily to achieve a consistent top brine temperature (TBT) in response to changes in available solar energy. The dynamic model simulation shows an average daily production of 7.6 kg of fresh water per unit area of the solar collector, with daily average output gain and recovery ratios of 0.3 and 0.09, respectively.